This invention relates to containers for raising plants for transplantation, and particularly to improvements in containers which provide a container planting system superior to other known systems, and which provides an adaptability not found in other plant container systems.
Horticulture and forestry practices recently have undergone changes in techniques. Industrial ideas have been applied to these practices to make the two disciplines more efficient than in the past. Standardization of product, mass handling systems, and a "product engineering" approach to growing plants has resulted. Among the systems now practised is one known as "Container Planting", where a plant is kept in a standard container, not unlike a flower pot, and is protected during the critical stages in its early growth. The container is used throughout all the rearing stages, before final transplanting occurs, and this would include seeding and/or placing a cutting into a container.
Man has long recognized the need to replace forests, and reforestation has been extensively practised in many areas. Reforestation has been carried out by a number of different methods, including:
1. the natural method, whereby a forested area is allowed to regenerate itself; and
2. the nursery method.
The natural method of reforestation, as will be appreciated, is haphazard.
Nurseries were the first step in meeting some of the demand for new trees. In the nursery method of reforestation seed is collected, prepared, sowed in long narrow beds in as dense concentration as possible, and covered with mulch; the beds are watered and the seedlings tended as they germinate, sprout and begin to grow. Two years later, when the seedlings are three to five inches high, they are dug up, the uppromising ones are culled, and the seedlings are transplanted by machine into other beds, and spaced out to allow further growth. After a further two years, the seedlings are considered strong enough to stand transplanting at their final site, and are then uprooted again and moved out to the forest. This method still is used; however, it has been at least partially supplanted by a newer nethod, container planting.
Largely as a result of the needs of reforestation programs, a good deal of work has been carried out in recent years to develop improved methods and equipment for growing and planting seedlings. One promising method, with which this invention is concerned, is known as container planting, and this method has become a useful addition to the nurseryman's techniques. The time-honored method of raising seedlings in a nursery bed has some disadvantages, notably the lack of control over disease, the damage to seedlings from pests and weather, and the tendency of certain tree varieties to send out long roots which would need to be pruned before the tree could be removed, transported, and transplanted. Such pruning has often set back a seedling's growth or caused deformation and weakening of the root system.
The "container" method involves providing a large number of cell-defining containers. The containers are filled with a growing medium, such as peat moss, and a seed is planted in each cell. After covering with grit or mulch, the seeds are permitted to germinate, and after they begin to grow, the young seedlings may be kept in a greenhouse from 4 weeks to 8 months depending on the variety and on the available environmental control. At this point, the seedlings may be set out into a shaded area to acclimatize them to normal conditions before being transplanted. In some cases, a dormant condition is desired for transplanting, so the young seedlings may be specially treated with fertilizers, or in addition may be slowly cooled. In the planting season, the seedlings are transported to the planting site directly in their containers, and kept in them for as long a time as possible. The planting operation is commonly carried out by a three-man crew. One of the crew carries the containers and distributes them to the other two; these men, the planters, each form cavities in the soil with a dibble stick, extract the seedlings and attached root balls from the cells and tamp them into the cavities.
A good container is one of the keys to the success of this system. In the greenhouse stage, the container should provide cells which foster the development of a thick system of roots. Without a good root structure, the plant will usually not survive in the field. For the purposes of the planting stage, the container should be a compact article which can be easily handled by the planters and which is adapted to permit efficient extraction of the seedling and root ball in an undamaged condition from the cell.
Advantages of container planting are as follows: 1. Each seedling is given an individual, non-competitive, controlled environment in which to grow and develop. 2. Seedling production -- seeding, thinning, weeding, atmosphere, fertilization, light control, temperature regulation and above all, handling, can be mechanized. 3. Seedlings are not "shocked" by transplanting, since they are in individual "pots" and the roots do not get damaged during this mechanical operation. 4. Because the seedlings will not be "shocked" they may be transplanted during summer months on a regular, weekly or daily basis. High productivity of labor and facilities, high survival rates and tangible good results are realized.
The prior art containers used in reforestation projects can be classified into two broad groups. The first group comprises plastic trays or blocks having rows of separate, tapered cells formed in them. To extract the seedling and root bulb from this type of cell, one grasps the seedling, at a time when the peat moss has become root bound, and simply pulls it out. A problem with this type of tray is that the time when the ball is root bound dictates when planting can be carried out. Another disadvantage is that the trays are quite bulky and relatively large quantities of plastic are used in making them. The second group of containers comprises a single cell unit, such as a paper or plastic cylinder. Most containers of this type are buried in the soil together with the root ball, and seedling. Because the only egress available to the roots is straight down through the open end of the container, there is initially little lateral growth of the roots. As a result, the plant is not well anchored during its early development; this leads to poor growth and a high mortality rate due to causes such as frost heaving. Another defect of this type of container is that the amount of labor required to handle large numbers of individual, separate cells is higher than is the case with multiple-cell units.
A distinct drawback to the use of the above type of planting container, which is intended to be allowed to degrade and is therefore left in the ground, is that the soil bacteria, the temperature, and generally the climate, must be just right or else the degradation of the container will take place too slowly, causing problems with root entrapment and deformation of the transplanted seedling.
Container planting involves the use of environmental control during germination and early growth, providing healthy plants with a good chance of survival after transplanting, and specifically allows tree seedlings to grow in individual cells. A problem with many varieties of plant containers has been their need to have long and deep cells for handing tap root development or to enable the transplanted seedling to reach a low water table. Ordinary pots or deep cells of this kind do not allow easy removal of the seedlings for transplanting until the whole volume has been filled with roots. Sinch such root-binding is undesirable horticulturally, it is useful to have an easy method of withdrawal, which allows the whole plug of roots and soil medium to be handled without damage and to be placed without any restrictive covering into the transplanting site.
The present invention provides the above advantage, and also allows for easy inspection of root development without disturbing the root system or straining the stem or trunk of the seedling. It is either a folding planter or one made in two halves, single or multiple, which can be removed from a box and opened easily, without restriction, along an axial split to reveal the root system for examination or easy removal for planting or culling. The same container(s) and plant(s) may then be closed and replaced in the box, which in turn hold the two sides together in each container. Although there is no frictional joint to slow down the process of opening or closing the container(s), there is a shiplap joint which provides a long and difficult path for probing roots to traverse and escape into adjoining containers.
Within the walls of the container(s) of this invention and formed into the sides are longitudinal grooves, which catch and hold roots as they develop, and prevent roots from spiralling, which is the roots' natural tendency when they reach a smooth-walled surface. At the bottom of the contrainer(s) the growing medium must be supported, yet as large as possible an opening is maintained to provide space for developing roots. In practice, roots are allowed to emerge from the bottom of the container(s) but are prevented from growing further by circulation of air under the container(s). The grooves are able to direct outside roots straight toward this opening, and since the roots in them are also straight, these roots become end-withered quickly. As the plant has certain root-promoting qualities which are frustrated by this, it throws out branches of roots which repeat the process.
It is therefore an objective of this invention to provide a container whose structure is adapted to direct root growth to an air-pruning aperture to promote the growth of a thick root system having relatively straight roots.
It is another objective to provide a container from which the seedling and root ball can be easily extracted at any time for planting.
An addition preferred objective of this invention is to provide a container having a large air-pruning aperture.
It is a further preferred objective of this invention to provide a container having a number of cells for raising seedlings.
Still another objective of the invention is to provide a compact container which is easily handled and which is made from a relatively small quantity of plastic.
In accordance with one aspect of this invention, a container is provided having a large root-pruning aperture at its base together with a number of circumferentially spaced, downwardly-extending root grooves formed by the interior surface of the container's side wall. The roots of the seedling grow laterally out to the container side wall and then follow the root grooves down to the aperture -- on contacting air, which is of course devoid of nutrients, the roots wither, with the result that new roots sprout, thereby developing a thick root system.
In accordance with a preferred form of the invention, a multiple-cell, single row container is provided. It is split longitudinally and preferably hinged along its bottom edges so that it can be opened to expose the contents of its two halves. To extract the seedling from one of the cells, the planter opens the container and holds it in the palm of one of his hands, as one would do with a book, or places it in a carrying pouch, and uses his other hand to gently pry the exposed root ball free. At the same time, he may flex the thin-walled, flexible sheet plastic container to aid in releasing the root ball. In the greenhouse, the containers are tightly packed together in rows in a tray or box; the walls of the tray or box act to hold the containers closed. The structure of the container is such that it can be formed from a single, thin sheet of plastic; the consumption of raw material in manufacturing it is therefore kept to a minimum.
For mass production, it is more economical to have the containers in ganged and hinged "books" which are held closed within the confines of a foraminous-bottomed box. Several variations of this version with and without the hinges are possible. For individual plant sales or for such applications as when the grower may wish to keep individual plants separate, a tube-like container may be provided with most of the above-mentioned specific features which are improvements to container planting, and in addition some other features especially suited to the individual container.
A common feature of these containers is the form of the side walls of the container, which contain multiple grooves or flutes (more than four) which extend throughout the full effective length of the container to direct roots to the opening at the bottom. When filled with a growing medium, plants grow roots in each container, which roots are directly channeled toward the bottom by being trapped in these grooves or between ridges of the flutes. By the term "effective length", is meant that part of the container which contains the growing medium.
Another common feature of these containers is their combination with a box, tray or comparable flat-bottomed holder which holds them in a satisfactory position for filling, either by having the box or tray made with a foraminous bottom which will not allow the growing medium to fall through (but will allow the roots to penetrate) or by preventing the folding "books" from coming open, or both.
Another common feature of these containers is their substantially constant cross section throughout their effective length, which gives the roots as much unrestricted volume as possible, and assists in maintaining a tight pack of containers for vibration filling, the box or tray being the holding fixture with vertical parallel sides, and the containers being fitted tightly into the box.
A specific feature of the folding ganged container is its hinged design, which allows the ganged container (when removed from the holding box or tray) to be opened and closed like a book so that the progress of fertilization may be studied. In early development of the plants, during climatic changes which provide more or less humidity and more or less heat, development of the plant may not match the fertilizer regimen that has been chosen. In a case for example, where fertilizer has built up and salts have collected in the containers, the roots may rot out, unless the excess fertilizer is leached through by plain water. Such conditions are not easy to discern unless the state of the roots can be inspected. In other containers, it is difficult to remove the "plug" of growing medium without damaging the root structure. Hence it is important to be able to open the container on a hinge and to close it up again without disturbing the plant, and this invention provides an easily opened container without snaps, catches or friction locks.
The present invention in one broad aspect resides in a container for growing seedlings, said container being normally upstanding when in use and comprising a pair of first and second wall members, each formed of thin-walled, flexible, substantially non-porous sheet plastic. Each said wall member comprises a series of spaced, inwardly-projecting, elongate shoulders integrally joined by webs, the shoulders of the first wall member being mutually opposed relative to the shoulders of the second wall member, and said mutually opposed shoulders are provided with inter-engaging means, whereby when the wall members are pressed together, a series of open-topped cells are formed, defined by the shoulders and their connecting webs and closed along the greatest part of their length. The aforesaid shoulders and webs combine to form a series of parallel, inwardly-directed, relatively broad, deep grooves within said shoulders. Said grooves extend perpendicularly downwardly from the wall members' upper edge portions, and the lower end portions of each pair of opposed webs and integrally joined shoulders combine to form the base of each cell, within which is formed an aperture, which aperture is smaller than the aperture at the top of the cell; said webs constituting the predominant portion of the side walls of the container, and each pair of opposed webs forming the side walls of an individual cell of said series of cells. Each said web is corrugated longitudinally of said cell, the grooves of the corrugations on the interior side walls of each said cell extending downwardly directly toward the base aperture and constituting a series of root grooves for directing root growth toward said aperture. Also included are hinge means connecting the wall members at their lower ends.
In another broad aspect, this invention resides in the combination of a plurality of seedling-growing containers as defined above, and a holder for the containers. The holder is one which has side and end walls and a flat, foraminous bottom, and is suitably a box or tray. The containers are disposed in abutting relationship both with respect to each other and to the walls of the holder, and fill the holder.